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tentacles
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chloric: dann has tried with homemade "SnCl4" and had poor results. I believe his successful ATO coatings have used purchased SnCl4(-5H2O?).
[Edited on 20-2-2008 by tentacles]
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hashashan
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as I know you cant make persulfates with PbO2 .... the sulfuric acid will destroy the anode
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dann2
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Hello,
The anode has only been going for two days as I could not get around to setting it up.
Ti cathodes (4)
2.150 liters of Saturated NaCl
10 amps (250mA per square cm on anode)
Added NaF
I am stirring using a homemade magnetic stirrer made from power supply fan with HD magnet stuck to it. (works good but stirring bar making alot of
noise)
I hope to titrate some of the solution every two days or so and track formation of Chlorate and then the destruction of Chlorate (Perchlorate forming)
all the way to the 'end'. I will not be measuring Perchlorate or Chloride.
Will also track pH and temperature and voltage but the pH I suppose is the one of most interest.
Regarding the ATO undercoat. It was make with purchased SnCl4:5H2O (Laboratory reagent grade). 'Antimony Chloride' was made from ceramic grade
Antimony Oxide.
All efforts that I made to get SnO2 coat from SnCl2 or 'homemade' SnCl4 were a failure.
Perhaps SnCl4 (anhydrous (liquid)) would do for making an undercoat. It appears in some of the patents for use as a bare Tin Oxide anode. SnCl4
(anhydrous) is not that hard to make (depends on what you call hard I guess), you need Tin and dry Chlorine gas.
The Alpha Lead Dioxide is more compatible with ATO, has better adhesion and deposits more smoothly so you will not get as many humps and bumps as you
start to plate. It is good start for the Beta which is inclined to go 'humpy and bumpy' if you have sharp corners.
I am going to get a cheap sand blaster. Perhaps I will not get around to using it on an anode.
The original report of this type of anode in the amateur world is here, from 10 Febuary 2004:
http://www.sciencemadness.org/talk/viewthread.php?tid=1425&a...
Dann2
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dann2
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Hello,
The cell running the Lead Dioxide anode sprang a leak today. The magnetic stirrer bar wore a hole in the bottom of the plexiglass container.
Luckely only 160ml leaked out (2 liter cell).
Started again is a shallower cell, no stirring needed. I have abandoned measureing Chlorate concentration all the way to the end as I had to add
500ml more salt solution for the new cell.
Will moniter my next cell. The ph of the current cell went to about 10.2 at the start and then down to 9.2 after about 3 days. Perchlorate had started
to form.
This was a bit too soon. I think that since the cell was very tall and the magnetic stirrer was stopping every now and then, this caused a 'micro
cell' (0.9 l)
to form at the top of the container. Its temperature was going to 72c as it was not mixing with the bottom half.
Dann 2
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hashashan
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Well I know I promised to post pics of my anode like half a year ago ... here they are.
I don't have pics of it not installed in the cell ... as soon as Ill disassemble this cell Ill post some raw pics also.
the white goo on the anode is the remains of the hot melt glue I used to stop it from forming in some places. and the mess on the top was once the
silver connection, It was heavily eroded because of some leeking gasses or liquids
Also It is a bit smaller now, because a bit of it broke off.
[Edited on 27-2-2008 by hashashan]
[Edited on 27-2-2008 by hashashan]
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dann2
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Hello Hashashan,
A cathode both sizes would be better. Since the andoe is not smooth its apparent area is much bigger that the measured area. So you current density
may be less that you imagine. Then again since there is only a cathode on one side the current density on that side will be more that estimated. As
clear as mud I guess.
Thanks for picks.
Dann2
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hashashan
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Id love to put one more cathode but I dont have any more Ti. and I dont want to mess up the liquor with anyhting
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dann2
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Hello,
I titrated some samples that came from my cell (before it sprang a leak).
Over a 22.5 hour period the Chlorate concentration increased 29 grams in the cell.
Running at 10 amps this is a staggering (we waaaa) 20% CE. WTF
Similar results from other samples. I got an appprox. straight line graph (four samples + zero at start).
Current density is 250mA per square cm on anode.
I think me LD needs a smathering of Bi !?
Dann2
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hashashan
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How wouldyou dope in some Bi?
how about to dope some Ti inside, hoping for the conductive oxide?
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dann2
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Hello,
US 4,101,390 and US 4,038,170 (similar patents) say that Bi will help wear rate of LD anode. Bi is also supposed to be good at making Perk. The
patents say the advantage is in cold solutions (for reduced wear). May make no difference in warm, non-pH controlled Chlorate cells.
There may be more pats on Bi helping wear rated.
Regarding my low current efficiency. I wonder would it be the cathodes. I have read articles where they got very different CE when different cathodes
were used. 20% is pathetic. I am using Ti.
Or perhaps a lower Current density may help.
Will have to do something about it.
Dann2
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tentacles
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dann, I looked back and don't see a mention of whether you used an efficiency additive; NaF or persulfate?
[Edited on 28-2-2008 by tentacles]
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dann2
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Hello,
I used 2 grams per liter NaF (added at start).
I am going to try lowering the temp. by putting the cell into a container of water.
If that does not work I will lower Current density on anode.
I leave the cell for 24 hours after each change, take a sample and titrate. This is handy to do once you have your solutions made up.
Dann2
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hashashan
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Hi, I have a possible good wa to make a PbO2 anode.
Yesterday I went to a jewlery shop to buy some silver for a good contact and I found there something interesting, a Ti mesh. but not just a Ti mesh...
it is a very fine mesh, looks just like fabric, very thin(the strands are thinner then human hair). The mesh is about 3mm diameter sleeve.
So I thought, why not put that sleeve on some sort of substrate and deposit a layer of PbO2 on it.
It is seems like a cheap and reliable method.
There is a problem, what would be the best substrate? my thoughts are :
some sort of plastic :
ADVANTAGES: cheap, easy to find, easy to handle, the liquer wotn harm it.
DISADVANTAGES : If there will be a bad connection that will cause heat, the plastic will melt and might even catch fire. and it wont conduct
heat out
Glass :
ADVANTAGES : quite cheap, the liquer wont harm it, neither will it melt nor catch fire upon heating.
DISADVANTAGES : not that easy to find in the right size, hard to handle, might break uopn rapid heating, wont conduct hreat out.
Epoxy :
ADVANTAGES : cheap, quite easy to handle, wont break or disintegrate upon reasonable heating.
DISADVANTGES : might take fire, wont conduct heat out
any other suggestions?
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dann2
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Hello Hashashan,
Will the Ti mesh be any better than say (as you used) the Scotch cloth?
You will not be able to use the Ti as the current carrier to the anode when it goes into a (Per)Chlorate cell (as you said) as the Ti/LD interface
will passivate no matter how thick the coating of LD is.
You are really back to the massive anode with cloth reinforcing, this time the cloth is Ti.
US Pat 850380
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
is somewhat similar. It uses a Ta substrate (its really a massive anode).
You could use the Ti mesh to carry current in the plating bath so long as you start with a near neutral Nitrate bath or start with a coating of Alpha
from an alkali bath and then plate Beta. The 'substrate' (piece of plastic, glass or whatever) would simply be keeping the mesh straight.
If you used something that could be removed (wax?) you would end up with a novel, tubular anode (better than anything before, best ever, etc etc  )
The 3mm is too small for this though.
Is it expensive?
Make sure it is actually Ti metal and not like this:
http://cgi.ebay.co.uk/WIRE-MESH-RIBBON-VERSATILE-ORIGINAL-TI...
Dann2
[Edited on 4-3-2008 by dann2]
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hashashan
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I don't want a massive anode, All I want is about 1mm coating and a hard substrate underneath(just mechanical strength)
the Current will be applied through a silver coating.
What is so good with PbO2 tube?
It costs about 7$ per meter.. not too expensive.
I don't know if it is pure Ti, that is what I have been told, it is anodized but still conducts current.
I will probably use glass as substrate, It can also be removed easily if necessary after the coating application.
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dann2
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Hello,
About the tube shaped anode I was only joking that it was better than anything before etc etc (patent speek as it were), though a tube shaped anode if
you manage to make one would be stronger and more robust (physically) than a flat anode of the same surface area. You would need to put a cathode
inside if you intended to use the inside surface. That would take a bit of accurate positioning if the tube is only 3mm diameter.
You can find out if it is Ti by putting a small amount into a Chlorate cell as an anode. If the current flows for a few seconds and then fades away it
is a valve metal. If the current keeps flowing then it is something else and will not be suitable. Do not use over 10 volts.
Cheers,
Dann2
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hashashan
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Dude I don't care if it is Ti as long as It will handle the first plating. ... well just see.
I found out how much a quartz tube of such diameter will cost .... god damn 90 euros per meter(I almost shit myself), I think Ill use glass and see
what happens
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dann2
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Hello,
The LD Anode is still going OK (one month). The current efficiency is very low. (20%)
I tried lowering current density. CE got worse.
Lowering temp. with CD kept at 250mA per square cm. CE went up to 26%.
I added 2 grams per liter Sodium Persulphate. The current efficience went up to 38%, but it came back down again when I added a mild steel cathode. I
am not saying that the CE decreased because of the mild steel cathode addition, it looked more like the 'effect' of the Persulphate wore off the cell
(if ya know what I mean, cos I am not too sure meself!!!). There was an absolutely horrible stink when I added the Na Persulphate to the cell. What
was it doen anyone care to guess. Ozone? I don't think it was Chlorine.
I added a mild steel cathode (instead of the Ti cathodes that the cell was running with from the start), and the current efficiency came down to about
15%.
I am doing too much chopping and chaging. I take sample but don't have time to titrate for some days after.
It is slowly but surly going towards a Perchlorate cell. It contains 300g per liter Chlorate at this stage. (It started with 300g per liter Chloride
when it was started).
I added 2g/l NaF at start BTW. Cell is 2.65L. Current is now 10 amps. V is about 4.8 volts.
Anode OK though which is good.
@Hashashan
You got approx. 50% CE but then again you had trouble getting rid of Chlorate when you went to destroy it. Perhaps you have much more Chlorate than
you thing (less CE than you think?)
@Anyone else measure CE with LD anode here?
Cheers,
Dann2
[Edited on 24-3-2008 by dann2]
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hashashan
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dann' most probably you are right. Its just that i usually got a positive test with MB after twice the theoretical time.. the chlorate->
perchlorate was quite slow probably.
what is the CE of Pt anode?
and how do people get up to 80% with LD?
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tentacles
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Pt and LD can have similar (for our intents and purposes) efficiencies.. the problem is, to get high efficiency you need to control the cell pH
carefully. Realistically, you'd need something like a pH controller and a small pump to dose the dilute HCl into the cell. Might not be terribly
expensive - an aquarium/hydroponics pH controller runs about $150 I believe.
But then again, you'd need a pH probe that can survive in a chlorate/perchlorate cell long term! I don't know if any could do that, but there are
probably ones that will.
[Edited on 24-3-2008 by tentacles]
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dann2
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Hello,
@Hashashan
If you got Perchlorate forming in good amounts at twice the 'run time' then you did not get too bad of a Current Efficiency (CE), approx 50%. When you
say 'twice the run time', do you mean the run time of (theoretically) converting all the Chloride to Chlorate or all the way to Perchlorate.
Perhaps Pt has better CE in a non pH controlled cell that LD. All articles that you read comparing/discussing Pt/LD will be in relation to pH
controlled cells.
I always though that you got about 50% CE when pH was not controlled and way up at 80 to 95% CE when pH was controlled. Approx. 50% is what people
get when using Graphite (no pH controll). Lots of people have done it, but not many have used LD down the years because they just did not have the
stuff (failed anodes etc).
I am currently controlling the pH of my Magnetite anode cell. It seems to be quite easy to do. I guestimated that I would need 0.2ml 12% HCl per hour
into the cell. Set up my syringe pump to put 0.2ml per hour into it and it is holding the pH steady at 6.8/6.9 (bang on target). I am checking the pH
every half day or so using a pH meter calibrated with a buffer solution at pH 7. Will measure CE in a few days and see what is the story.
Will then pH controll my LD cell and see how it does regarding CE.
Syringe pumps can be had on ebay for about 100 bucks.
Dont see why a cheap intravanous drip (bag hanging up with a tube and dripper yoke) would not do the job. Perhaps the pH will have a tendency to self
control. If you add a small amount of acid too much, you will loose more Cl and pH will tend to increase etc etc. Perhaps no need for a pH meter in
cell all the time.
When using pH paper to measure pH it is difficult to get a reading as the paper gets bleached.
Can anyneo tell, if you boil a small quantity of the solution before measuring the pH to get rid of the bleaching effect (Hypochlorite???) will that
effect the pH measurement?
Suppose I could do this and see!
Dann2
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hashashan
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I meant the theoretical time for the chloride to convert to chlorate.
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tentacles
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50% is not bad at all for an uncontrolled cell, with any kind of anode.
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hashashan
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50% is great. but the chlorate-> perchlorate stage is much slower for some reason.
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dann2
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Hello,
Perhaps there is much more Chloride still not converted to Chlorate? and the anode is still busy converting this Chloride to the Chlorate (and forming
small amounts of Perchlorate at the same time) just a guess really.
Did you try adding some NaF or a Persulphate?
I attached an article from Ullman (thanks to KMnO4, no I'm not talking about Purple Haze...). It is a good read on Chlorate/Perchlorate stuff.
@Xenoid. It contains diagram of KCl and KClO3 mutual solubility.
Anyone access to French Journals??
Bull. Soc. Chim. France
A. Nallet, R. A. Paris.
1956, 488 – 494.
http://www.ingentaconnect.com/content/els/00378968
Not available online
Dann2
Attachment: Chlorine Oxides and Chlorine Oxygen Acids.pdf (819kB)
This file has been downloaded 2848 times
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